In information search, search technologies such as inversed indexing may be used to search a given character string in mass documents (such as webpages on the Internet). In a conventional inversed indexing technology, a character string to be searched is divided into tokens. Here, the term “token” refers to a unit composing a character string, such as a character, a word, a phrase, and the like. During the search, all documents including all tokens will be searched.
A biggest issue that this search faces is searching efficiency. It may be understood that for each token in the character string, there may be the considerable numbers of documents including the token. By contrast, in each document, each token may appear many times. A conventional search engine has to process all of these tokens in all documents. This significantly lowers the searching efficiency, which causes the search of the character string to become a time-consuming process. A sluggish response in turn degrades experiences of users who use the search engine.